The present invention relates to a new and improved construction of apparatus for the opto-electrical (also sometimes referred to as the electro-optical) determination of a measured value or magnitude at a viscosimeter, especially a rotational viscosimeter.
There are already known to the art different constructions of and differently operating systems for both measuring and indicating a measurement result during the measurement of the viscosity of a medium by means of a rotational viscosimeter. Two of the state-of-the-art systems will be briefly considered hereinafter. One such system, for instance as taught in Swiss Pat. No. 474,055, imparts a deflection out of a null-position to a rotatably mounted transmission housing owing to the action of the occurring braking moment. The angle of deflection of the housing constitutes a measure for the brake moment and thus for the viscosity of the medium and can be measured, for instance, by means of an electromagnetic system which has become known under the designation "Pick-Off". This measured deflection angle can then be read-off of an indicator device.
According to another prior art system, for instance as disclosed in German Pat. No. 1,648,858, the occurring brake moment is transmitted to a stator shaft which can be rocked against the restoring force of a torsion spring. The stator shaft is rotated out of a rest position together with a measuring indicator attached thereto as a function of the degree of the effective viscosity of the medium which is being measured, so that it is possible to read the viscosity of such medium by means of a suitable scale dial appropriately calibrated in degrees of viscosity and operatively associated with the measuring or measurement indicator.